Add dedicated definition for intrinsics

compiler/rustc_smir/src/rustc_smir/context.rs

@@ -23,8 +23,8 @@ use stable_mir::mir::{BinOp, Body, Place};
 use stable_mir::target::{MachineInfo, MachineSize};
 use stable_mir::ty::{
     AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, ForeignDef,
-    ForeignItemKind, GenericArgs, LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind, UintTy,
-    VariantDef,
+    ForeignItemKind, GenericArgs, IntrinsicDef, LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind,
+    UintTy, VariantDef,
 };
 use stable_mir::{Crate, CrateDef, CrateItem, CrateNum, DefId, Error, Filename, ItemKind, Symbol};
 use std::cell::RefCell;
@@ -307,6 +307,28 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         sig.stable(&mut *tables)
     }
 
+    fn intrinsic(&self, def: DefId) -> Option<IntrinsicDef> {
+        let mut tables = self.0.borrow_mut();
+        let tcx = tables.tcx;
+        let def_id = def.internal(&mut *tables, tcx);
+        let intrinsic = tcx.intrinsic_raw(def_id);
+        intrinsic.map(|_| IntrinsicDef(def))
+    }
+
+    fn intrinsic_name(&self, def: IntrinsicDef) -> Symbol {
+        let mut tables = self.0.borrow_mut();
+        let tcx = tables.tcx;
+        let def_id = def.0.internal(&mut *tables, tcx);
+        tcx.intrinsic(def_id).unwrap().name.to_string()
+    }
+
+    fn intrinsic_must_be_overridden(&self, def: IntrinsicDef) -> bool {
+        let mut tables = self.0.borrow_mut();
+        let tcx = tables.tcx;
+        let def_id = def.0.internal(&mut *tables, tcx);
+        tcx.intrinsic_raw(def_id).unwrap().must_be_overridden
+    }
+
     fn closure_sig(&self, args: &GenericArgs) -> PolyFnSig {
         let mut tables = self.0.borrow_mut();
         let tcx = tables.tcx;
@@ -645,16 +667,6 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         }
     }
 
-    /// Retrieve the plain intrinsic name of an instance.
-    ///
-    /// This assumes that the instance is an intrinsic.
-    fn intrinsic_name(&self, def: InstanceDef) -> Symbol {
-        let tables = self.0.borrow_mut();
-        let instance = tables.instances[def];
-        let intrinsic = tables.tcx.intrinsic(instance.def_id()).unwrap();
-        intrinsic.name.to_string()
-    }
-
     fn ty_layout(&self, ty: Ty) -> Result<Layout, Error> {
         let mut tables = self.0.borrow_mut();
         let tcx = tables.tcx;

compiler/stable_mir/src/compiler_interface.rs

@@ -13,8 +13,8 @@ use crate::target::MachineInfo;
 use crate::ty::{
     AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, ForeignDef,
     ForeignItemKind, ForeignModule, ForeignModuleDef, GenericArgs, GenericPredicates, Generics,
-    ImplDef, ImplTrait, LineInfo, PolyFnSig, RigidTy, Span, TraitDecl, TraitDef, Ty, TyKind,
-    UintTy, VariantDef,
+    ImplDef, ImplTrait, IntrinsicDef, LineInfo, PolyFnSig, RigidTy, Span, TraitDecl, TraitDef, Ty,
+    TyKind, UintTy, VariantDef,
 };
 use crate::{
     mir, Crate, CrateItem, CrateItems, CrateNum, DefId, Error, Filename, ImplTraitDecls, ItemKind,
@@ -88,6 +88,16 @@ pub trait Context {
     /// Retrieve the function signature for the given generic arguments.
     fn fn_sig(&self, def: FnDef, args: &GenericArgs) -> PolyFnSig;
 
+    /// Retrieve the intrinsic definition if the item corresponds one.
+    fn intrinsic(&self, item: DefId) -> Option<IntrinsicDef>;
+
+    /// Retrieve the plain function name of an intrinsic.
+    fn intrinsic_name(&self, def: IntrinsicDef) -> Symbol;
+
+    /// Returns whether the intrinsic has no meaningful body and all backends
+    /// need to shim all calls to it.
+    fn intrinsic_must_be_overridden(&self, def: IntrinsicDef) -> bool;
+
     /// Retrieve the closure signature for the given generic arguments.
     fn closure_sig(&self, args: &GenericArgs) -> PolyFnSig;
 
@@ -198,7 +208,6 @@ pub trait Context {
     fn vtable_allocation(&self, global_alloc: &GlobalAlloc) -> Option<AllocId>;
     fn krate(&self, def_id: DefId) -> Crate;
     fn instance_name(&self, def: InstanceDef, trimmed: bool) -> Symbol;
-    fn intrinsic_name(&self, def: InstanceDef) -> Symbol;
 
     /// Return information about the target machine.
     fn target_info(&self) -> MachineInfo;

compiler/stable_mir/src/mir/mono.rs

@@ -106,7 +106,9 @@ impl Instance {
     /// which is more convenient to match with intrinsic symbols.
     pub fn intrinsic_name(&self) -> Option<Symbol> {
         match self.kind {
-            InstanceKind::Intrinsic => Some(with(|context| context.intrinsic_name(self.def))),
+            InstanceKind::Intrinsic => {
+                Some(with(|context| context.intrinsic(self.def.def_id()).unwrap().fn_name()))
+            }
             InstanceKind::Item | InstanceKind::Virtual { .. } | InstanceKind::Shim => None,
         }
     }

compiler/stable_mir/src/ty.rs

@@ -622,6 +622,41 @@ impl FnDef {
     pub fn body(&self) -> Option<Body> {
         with(|ctx| ctx.has_body(self.0).then(|| ctx.mir_body(self.0)))
     }
+
+    /// Get the information of the intrinsic if this function is a definition of one.
+    pub fn as_intrinsic(&self) -> Option<IntrinsicDef> {
+        with(|cx| cx.intrinsic(self.def_id()))
+    }
+
+    /// Check if the function is an intrinsic.
+    #[inline]
+    pub fn is_intrinsic(&self) -> bool {
+        self.as_intrinsic().is_some()
+    }
+}
+
+crate_def! {
+    pub IntrinsicDef;
+}
+
+impl IntrinsicDef {
+    /// Returns the plain name of the intrinsic.
+    /// e.g., `transmute` for `core::intrinsics::transmute`.
+    pub fn fn_name(&self) -> Symbol {
+        with(|cx| cx.intrinsic_name(*self))
+    }
+
+    /// Returns whether the intrinsic has no meaningful body and all backends
+    /// need to shim all calls to it.
+    pub fn must_be_overridden(&self) -> bool {
+        with(|cx| cx.intrinsic_must_be_overridden(*self))
+    }
+}
+
+impl From<IntrinsicDef> for FnDef {
+    fn from(def: IntrinsicDef) -> Self {
+        FnDef(def.0)
+    }
 }
 
 crate_def! {

tests/ui-fulldeps/stable-mir/check_intrinsics.rs

@@ -11,6 +11,7 @@
 //@ ignore-windows-gnu mingw has troubles with linking https://github.com/rust-lang/rust/pull/116837
 
 #![feature(rustc_private)]
+#![feature(assert_matches)]
 
 extern crate rustc_hir;
 #[macro_use]
@@ -23,8 +24,8 @@ use rustc_smir::rustc_internal;
 use stable_mir::mir::mono::{Instance, InstanceKind};
 use stable_mir::mir::visit::{Location, MirVisitor};
 use stable_mir::mir::{LocalDecl, Terminator, TerminatorKind};
-use stable_mir::ty::{RigidTy, TyKind};
-use std::collections::HashSet;
+use stable_mir::ty::{FnDef, GenericArgs, RigidTy, TyKind};
+use std::assert_matches::assert_matches;
 use std::convert::TryFrom;
 use std::io::Write;
 use std::ops::ControlFlow;
@@ -39,9 +40,10 @@ fn test_intrinsics() -> ControlFlow<()> {
     visitor.visit_body(&main_body);
 
     let calls = visitor.calls;
-    assert_eq!(calls.len(), 2, "Expected 2 calls, but found: {calls:?}");
-    for intrinsic in &calls {
-        check_intrinsic(intrinsic)
+    assert_eq!(calls.len(), 3, "Expected 3 calls, but found: {calls:?}");
+    for (fn_def, args) in calls.into_iter() {
+        check_instance(&Instance::resolve(fn_def, &args).unwrap());
+        check_def(fn_def);
     }
 
     ControlFlow::Continue(())
@@ -53,22 +55,39 @@ fn test_intrinsics() -> ControlFlow<()> {
 ///
 /// If by any chance this test breaks because you changed how an intrinsic is implemented, please
 /// update the test to invoke a different intrinsic.
-fn check_intrinsic(intrinsic: &Instance) {
-    assert_eq!(intrinsic.kind, InstanceKind::Intrinsic);
-    let name = intrinsic.intrinsic_name().unwrap();
-    if intrinsic.has_body() {
-        let Some(body) = intrinsic.body() else { unreachable!("Expected a body") };
+fn check_instance(instance: &Instance) {
+    assert_eq!(instance.kind, InstanceKind::Intrinsic);
+    let name = instance.intrinsic_name().unwrap();
+    if instance.has_body() {
+        let Some(body) = instance.body() else { unreachable!("Expected a body") };
         assert!(!body.blocks.is_empty());
-        assert_eq!(&name, "likely");
+        assert_matches!(name.as_str(), "likely" | "vtable_size");
     } else {
-        assert!(intrinsic.body().is_none());
+        assert!(instance.body().is_none());
         assert_eq!(&name, "size_of_val");
     }
 }
 
+fn check_def(fn_def: FnDef) {
+    assert!(fn_def.is_intrinsic());
+    let intrinsic = fn_def.as_intrinsic().unwrap();
+    assert_eq!(fn_def, intrinsic.into());
+
+    let name = intrinsic.fn_name();
+    match name.as_str() {
+        "likely" | "size_of_val" => {
+            assert!(!intrinsic.must_be_overridden());
+        }
+        "vtable_size" => {
+            assert!(intrinsic.must_be_overridden());
+        }
+        _ => unreachable!("Unexpected intrinsic: {}", name),
+    }
+}
+
 struct CallsVisitor<'a> {
     locals: &'a [LocalDecl],
-    calls: HashSet<Instance>,
+    calls: Vec<(FnDef, GenericArgs)>,
 }
 
 impl<'a> MirVisitor for CallsVisitor<'a> {
@@ -77,10 +96,10 @@ impl<'a> MirVisitor for CallsVisitor<'a> {
             TerminatorKind::Call { func, .. } => {
                 let TyKind::RigidTy(RigidTy::FnDef(def, args)) =
                     func.ty(self.locals).unwrap().kind()
-                    else {
-                        return;
-                    };
-                self.calls.insert(Instance::resolve(def, &args).unwrap());
+                else {
+                    return;
+                };
+                self.calls.push((def, args.clone()));
             }
             _ => {}
         }
@@ -106,6 +125,7 @@ fn generate_input(path: &str) -> std::io::Result<()> {
         #![feature(core_intrinsics)]
         use std::intrinsics::*;
         pub fn use_intrinsics(init: bool) -> bool {{
+            let vtable_sz = unsafe {{ vtable_size(0 as *const ()) }};
             let sz = unsafe {{ size_of_val("hi") }};
             likely(init && sz == 2)
         }}